While taking the measurements around the airport for the dB level of overflying airplanes, we also take strait sound recordings using very accurate equipment. This data is then dumped into very powerful noise analysis software which gives us a frequency spectrogram. This graph (seen below) uses color to signify the intensity of a specific frequency. These spectrographs will then be compared between other spectrographs from either the same aircraft taken under different condition, such as weather, or see the how different aircraft's spectrographs compare to each other.
We hope that this information will allow us to determine how different
variables affect the frequencies that people hear from the aircraft, and
ultimately the sensitivity of the receiver due to the frequency.
For people's sensitivity to a sound is affected by the frequency of the
sound. Below is a graph, known as the Fletcher-Munson Scale that
we shall use to determine how sensitive people are to certain frequencies.
